Field of the Invention
The present invention relates to a mirror system for superimposing and displaying an arbitrary image on the reflected image of an object.
Description of the Related Art
There have been proposed various mirror systems for displaying not only a reflected image but also a video on a mirror surface.
As applications of such a mirror system, a rehabilitation system for recovering the functions of a human body and a system for determining the quality of physical exercises for maintaining health have been proposed. In these system applications, it is expected to achieve effective rehabilitation and training by presenting, on a mirror surface, a video (to be referred to as an “evaluation index video” hereinafter) serving as an evaluation index such as the posture evaluation result and a past state of a treatment acceptor, and model movement by a trainer simultaneously with the reflected image of the treatment acceptor.
In the proposed techniques, a diffusion layer (screen) is arranged on the rear side of a half mirror forming the mirror surface to present a video. If, therefore, the above-described system applications present the posture of the treatment acceptor and its evaluation index, the following problems arise.
Since the depth of an image presentation surface is fixed on the screen, an evaluation index video with a depth different from that of a reflected image is presented. That is, since the focal length and the angle of convergence of the reflected image of the treatment acceptor are different from those of an image (to be referred to as a “presentation image” hereinafter) presented as an evaluation index video, it is difficult for the treatment acceptor to simultaneously observe his/her reflected image and the presentation image without changing the fixation point.
If, for example, the treatment acceptor fixes the eye on his/her reflected image at a depth twice the space (distance) between the treatment acceptor and the mirror, the presentation image looks blurred because the binocular parallax of the reflected image does not coincide with that of the presentation image on the mirror surface. To the contrary, if the treatment acceptor fixes the eye on the presentation image on the mirror surface, his/her reflected image at a deeper position in the mirror looks blurred.
If the treatment acceptor moves forward or backward, the position of the reflected image changes according to the movement but the presentation image fixed on the screen cannot follow the forward or backward movement of the treatment acceptor.
To evaluate movement of the treatment acceptor, it may be possible to superimpose and display a bone or computer graphics (CG) image corresponding to the posture as an evaluation index video for each part. In this case, however, the treatment acceptor may take a posture in which the depths of the respective parts such as the head and four limbs are different from each other, and it is difficult in such a case to superimpose the evaluation index video of each part on the posture and observe it.
To solve the above problems, it may be possible to add depth to display of the evaluation index video by using a three-dimensional (3D) display as a video presentation apparatus on the rear side of the half mirror. Even if the 3D display is used, an actually presented video is on the screen. Since, therefore, the depth of the reflected image of the treatment acceptor is different from that of the evaluation index video due to the angle of convergence adjustment mechanism and the focus adjustment mechanism of human eyeballs, it is difficult to present an appropriate video to the treatment acceptor.